CN106867305A - A kind of modified CeO in surface2Nano material and product - Google Patents

Abstract

The invention discloses a surface _- modified CeO2 nanomaterial and its products, which belong to the field of perovskite solar cells. _The surface of the CeO2 nanoparticle is coated with bipolar organic molecules, so that the _CeO2 nanomaterial can simultaneously Uniform dispersion in polar and non-polar solvents. The present invention also provides a nano-ink, wherein the surface-modified CeO2 nano _- material is uniformly dispersed in a solvent. The present invention also provides an electron transport layer with a roughness less than 1 nm prepared by using the above nano-ink, and perovskite solar cells with three structures prepared by using the electron transport layer. _The CeO2 nanomaterial of the present invention has high electrical conductivity, high carrier mobility, simple preparation process, good chemical stability, and energy level matching with perovskite light-absorbing materials, which can ensure the photoelectric conversion efficiency of battery devices, and can also greatly Improve long-term stability of the device.

Description

A kind of surface-modified CeO2 nanometer material and product

technical field

The invention belongs to the technical field of perovskite solar cells, in particular to surface-modified CeO2 nanometer materials and products and the application of the _two materials in heterojunction solar cells.

Background technique

Coal, oil, natural gas, etc. are non-renewable energy sources, which will always be exhausted one day. In order to maintain sustained, stable and rapid economic growth, we will face severe energy problems. As the main source of energy for the earth, solar energy is abundant, clean and renewable. Governments of all countries will study solar cells based on photoelectric conversion, especially cheap solar cell technology, as an important part of the national sustainable development strategy and an important trend in the development of new energy technologies.

In recent years, perovskite solar cells have developed rapidly and have attracted extensive attention from energy workers. Its highest photoelectric conversion efficiency exceeds 22%, which is close to the efficiency of traditional silicon cells, and the wide source of raw materials and simple preparation process make perovskite solar cells a very competitive new green photovoltaic industry.

Perovskite solar cells are a type of battery in which perovskite materials are used as light-absorbing materials in solar cells. Perovskite materials are excited to generate electron-hole pairs after being irradiated by sunlight, and electrons are collected by electron transport materials and transferred to the interior. The cycle anode is circulated through the outer cycle to the inner cycle cathode, thereby catalytically reducing the hole transport material that has collected holes, forming a complete cycle. The transport of electron-hole pairs in the battery device is restricted by the conductivity and carrier mobility of the electron transport layer. Secondly, because the titanium ore material itself is easy to degrade in a water-oxygen environment, its stability is limited by the The stability of the interface layer on both sides is restricted. Therefore, the development of an efficient and stable inorganic charge transport layer is the key to the development of perovskite solar cells.

At present, the organic charge transport layer has high-efficiency conductivity, but its carrier mobility is low, and additional ion doping is required, and its chemical stability is poor, and it is easy to degrade in a water-oxygen environment. In addition, its molecular structure is complex, The purification process is cumbersome, the output is low, and the use cost is high. Amorphous inorganic charge transport materials represented by cuprous thiocyanate and cuprous iodide also limit their wide application due to problems such as low crystallinity, low device efficiency, and severe hysteresis. Inorganic charge transport materials represented by zinc oxide and tin oxide cannot be widely used in inorganic charge transport materials due to their inherent good dispersibility, and it is difficult to disperse in pure non-polar solvents, and even a small amount Polar solvents still have an aggressive effect on the perovskite layer.

Cerium oxide has the high carrier mobility of inorganic oxides, good electrical conductivity and mechanical properties, and its preparation method is simple, which can greatly reduce the cost of material preparation. In the commonly used cerium oxide preparation system, oleic acid coated with cerium oxide can slow down the hydrothermal reaction of cerium oxide, and synthesize monodisperse cerium oxide nanoparticles. However, oleic acid wrapped on the surface of cerium oxide nanoparticles is a long-chain organic molecule with poor conductivity and is extremely difficult to remove. Oleic acid is strongly adsorbed on the surface of cerium oxide through the carboxyl group, and can be completely desorbed in alkaline solution. However, after desorption, cerium oxide nanoparticles are poorly dispersed in various common solvents, making them unsuitable for direct preparation of charge transport layers.

Therefore, it is of great significance and challenging to develop inorganic charge transport materials that are inexpensive, widely applicable, efficient and stable, and can be used in both polar and nonpolar solvents.

Contents of the invention

Aiming at the problems of low carrier mobility, poor chemical stability, easy degradation in water and oxygen environment and high cost in the prior art, the present invention provides a surface _- modified highly dispersed CeO2 nanomaterial and its As a product, the _CeO2 nanometer material of the present invention has high electrical conductivity, high carrier mobility, simple preparation process, good chemical stability, and energy level matching with perovskite light-absorbing materials, so as to ensure the photoelectric conversion efficiency of battery devices, and can also be extremely Greatly improving the long-term stability of the device while reducing the material cost of the device can ultimately enhance the competitiveness of perovskite solar cells in renewable energy.

In order to achieve the above object, according to one aspect of the present invention, a kind of surface modified _{CeO2nanomaterial} is provided, _{CeO2nanoparticle} surface is wrapped with bipolar organic molecules, so that this _{CeO2nanomaterial} can be polarized at the same time. Evenly dispersed in solvents and non-polar solvents.

Further, the carbon chain length of the main chain of the bipolar organic molecule is not more than five carbon atoms.

Further, the bipolar organic molecule is acetylacetone. Acetylacetone can volatilize at low temperature, even if it is not wrapped _on the surface of CeO2 nanoparticles, it can also volatilize without affecting product performance.

Further, the particle size of the CeO ₂ nanoparticles is 1nm-100nm. _CeO2 nanoparticles with different crystal structures are applicable.

Further, the molar ratio of the acetylacetone to the CeO ₂ nanoparticles is less than 10000:1. With the prolongation of the surface modification reaction time, more acetylacetone was adsorbed on the surface of CeO ₂ nanoparticles, and the dispersion of the modified product was better, but the corresponding electrical conductivity would be slightly reduced.

In the above inventive concepts, the bipolar organic molecules have short chains, and the bipolar organic molecules are wrapped or adsorbed on the surface of CeO ₂ particles. The short chain organic dangling bonds can increase the force between particles, reduce the distance between particles, and improve the Density, stability and conductivity of the electron transport layer. In addition, the remaining modifiers in the solution that are not adsorbed _on the surface of CeO2 nanoparticles can be volatilized at low temperature, and do not need to be treated at high temperature, and the perovskite light-absorbing layer will not be damaged due to high temperature.

According to a second aspect of the present invention, there is also provided a nano-ink, which includes a solvent, and also includes the surface-modified CeO nanomaterial as described above, and the surface _- modified CeO nano _- material is uniformly dispersed in the solvent . In the nano-ink, the mass concentration of the surface-modified CeO2 nano _- material can be 0-3 g/ml.

According to the third aspect of the present invention, there is also provided an electron transport layer for a battery, which is prepared by using the above-mentioned nano-ink, and its roughness is less than 1 nm. Common methods of nano-ink film formation such as spin coating, drop coating, doctor blade coating and extrusion coating can be used to obtain an electron transport layer with a single layer thickness of 1 nanometer to 1000 nanometers. Polar and non-polar solutions can be used alternately to prepare multilayer electron transport layers.

According to a fourth aspect of the present invention, a formal planar perovskite solar cell is also provided, which includes a conductive substrate, an electron transport layer, a perovskite light-absorbing layer, a hole transport layer, and a metal electrode. A transport layer, a perovskite light-absorbing layer, and a hole transport layer are sequentially stacked, the metal electrode is electrically connected to the hole transport layer, and the electron transport layer is an electron transport layer as defined above, and its thickness is less than 100 nm or more. The light transmittance of the electron transport layer is ensured.

According to a fifth aspect of the present invention, there is also provided a trans-type single-layer electron transport layer planar perovskite solar cell, which includes a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer, and a metal electrode, The conductive substrate, the hole transport layer, the perovskite light-absorbing layer, and the electron transport layer are sequentially stacked, the metal electrode is electrically connected to the electron transport layer, and the electron transport layer is the electron transport layer as defined above.

According to the sixth aspect of the present invention, there is also provided a trans-type double-layer electron transport layer planar perovskite solar cell, which includes a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, a first electron transport layer, a second Two electron transport layers and a metal electrode, the conductive substrate, the hole transport layer, the perovskite light-absorbing layer, the first electron transport layer, and the second electron transport layer are stacked in sequence, and the metal electrode and the second electron transport layer Electrically connected, the second electron transport layer is the electron transport layer as defined above, and the electrical conductivity of the first electron transport layer is not less than the electrical conductivity of the second electron transport layer.

Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

In the present invention, bipolar organic molecules are used to wrap or adsorb CeO2 nanoparticles, so that the _CeO2 nanomaterials can be uniformly dispersed in polar solvents and non _- polar solvents at the same time, and the high carrier of cerium oxide can be utilized The advantages of mobility, good electrical conductivity, and mechanical properties, as well as the simple preparation method also overcome the disadvantages of poor conductivity of CeO2 nanoparticles caused by oleic _acid encapsulation, high processing temperature and damage to the perovskite light-absorbing layer. _The modified CeO2 nanomaterials can be uniformly dispersed in polar solvents and non-polar solvents at the same time, and can also reduce the erosion of solvents on adjacent functional layers in batteries with different structures.

Furthermore, acetylacetone is a bipolar short-chain organic molecule, which can be well miscible with various polar and non-polar solvents. After the cerium oxide nanoparticles are modified with acetylacetone, the molecular chains are short, which does not hinder the transport of charges and carriers between the nanoparticles. This surface-modified highly dispersed material has low preparation cost and good photovoltaic properties, and has shown fascinating performance and potential application value in perovskite solar cells. _The modified CeO2 nanometer material of the invention can effectively improve the stability of battery devices, reduce the material cost of battery devices, and is beneficial to the large-scale industrial application of this type of batteries.

Description of drawings

Fig. 1 is the field emission transmission electron microscope picture of unmodified _{CeO2nanoparticle} ;

Fig. 2 (a), Fig. ₂ (b) are unmodified CeO Nanoparticles high-resolution transmission electron microscope picture and selected area diffraction picture;

Fig. ₃ is the XRD diffractogram of unmodified CeO nanoparticle;

Fig. ₄ CeO in the embodiment of the present invention The schematic diagram of the modification of nanoparticles;

Fig. 5 is the infrared spectrum comparison diagram of CeO2 nanoparticles in different stages in the surface modification process of Example ₁ , including oleic acid (Oleic acid) solvent, acetylacetone (Acetylacetine) solvent, ethanol cleaning cerium oxide coated with oleic acid (Rinsed), cerium oxide (Desorption) after alkaline solvent desorption, cerium oxide (Redispersion) after acetylacetone modification Infrared spectrum comparison chart, according to the English words in the figure to distinguish CeO ₂ nanoparticles in different stages;

Fig. 6 is the optical photo contrast figure of the CeO2 nanoparticle dispersion state in the solvent at different stages in the surface modification process of embodiment _two , including the toluene solution (R insed) of the cerium _oxide after cleaning, the clean CeO2 after desorption Comparison of optical photos of nanoparticles dispersed in ethanol (Desorption), modified CeO2 nanomaterials dispersed in methanol (Methanol), modified CeO2 nanomaterials dispersed in chlorobenzene _{( Chlobenzene} ), according to the figure The Chinese and English words distinguish the dispersion state of CeO ₂ nanoparticles in the solvent at different stages;

Fig. 7 is the front scanning electron micrograph of the thin film prepared by the CeO after the surface modification of embodiment _two ;

Fig. 8 is the CeO after the surface modification of embodiment _two The atomic force microscope figure of the thin film that nanoparticle prepares;

Fig. 9 is the transmission spectrogram of the film prepared by CeO after surface modification of embodiment _two ;

Fig. 10 is the fluorescence spectrogram of CeO2 nanoparticle preparation film after embodiment _two surface modification; Wherein, emission peak (Fluorescence peak) is at 440 nanometers, and 470 nanometers place is xenon lamp peak (Xenon lamp peak), 630 nanometers place is Raman peak (Raman peak);

Fig. 11 is the CeO after the surface modification of embodiment _two Nanoparticles prepare film's ultraviolet photoelectron spectrum (UPS, Ultroviolet Photoelectron Spectrometer) figure;

Fig. 12 is CeO after embodiment _two surface modification Nanoparticles prepare film's forbidden band width (Bandgap) figure;

Fig. 13 is the X-ray photoelectron spectrum (XPS, X-ray Photoelectron Spectrometer) figure of the thin film prepared by the CeO after the surface modification of embodiment _two ;

Fig. 14 is the high-resolution X-ray photoelectron spectrum of the cerium element of the thin film prepared by the CeO after the surface modification of embodiment _two ;

Fig. 15 is the high-resolution X-ray photoelectron spectrogram of the oxygen element of the thin film prepared by the CeO after the surface modification of embodiment _two ;

Fig. 16 is a cell device structure diagram of a formal planar perovskite solar cell in Example 3, wherein, 1 is an indium doped tin oxide (ITO, Indium doped tin oxide) conductive glass, and 2 is a modified cerium oxide electron transport layer, 3 is a perovskite light-absorbing layer, 4 is a hole transport layer, and 5 is a gold electrode;

Fig. 17 is the photovoltaic curve of the third formal planar perovskite solar cell device under a standard sunlight intensity;

Fig. 18 is a battery device structure diagram of a battery device with a trans-type single-layer electron transport layer planar battery structure in Embodiment 4. Among them, 6 is a fluorine doped tin oxide (FTO, Fluorine doped tin oxide) conductive glass, 7 is a nickel magnesium oxide lithium hole transport layer, 3 is a perovskite light-absorbing layer, 8 is a cerium oxide electron transport layer wrapped in oleic acid, 9 is a silver electrode;

Fig. 19 is the photovoltaic curve of the cell device with the planar cell structure of the four trans-type single-layer electron transport layer under a standard sunlight intensity;

Figure 20 is a battery device structure diagram of a battery device with a planar battery structure of a trans-type single-layer electron transport layer in Example 5, wherein 6 is a fluorine-doped tin oxide conductive glass, 7 is a nickel-magnesium-oxylithium hole-transport layer, and 3 is calcium Titanium ore light-absorbing layer, 2 is the modified cerium oxide electron transport layer, and 9 is the silver electrode;

Fig. 21 is the photovoltaic curve of the battery device with the planar battery structure of the trans-type single-layer electron transport layer of the embodiment 5 under a standard sunlight intensity;

Fig. 22 is a battery device structure diagram of a battery device with a planar battery structure of a six-trans type single-layer electron transport layer according to the embodiment. Among them, 6 is a fluorine-doped tin oxide conductive glass, 7 is a nickel magnesium oxide lithium hole transport layer, 3 is a perovskite light-absorbing layer, 10 is an organic electron transport layer, and 9 is a silver electrode;

Fig. 23 is the photovoltaic curve of the battery device with the planar battery structure of the six-trans type single-layer electron transport layer under a standard sunlight intensity;

Fig. 24 is a structural diagram of a battery device with a planar battery structure of a trans-type double-layer electron transport layer in Example 7. Among them, 6 is fluorine-doped tin oxide conductive glass, 7 is nickel magnesium oxide lithium hole transport layer, 3 is perovskite light-absorbing layer, 10 is organic electron transport layer (that is, the first electron transport layer), 2 is modified The final cerium oxide is used as the upper electron transport layer (i.e. the second electron transport layer), and 9 is a silver electrode;

Fig. 25 is the photovoltaic curve of the cell device with the planar cell structure of the trans-type double-layer electron transport layer in embodiment 7 under a standard sunlight intensity;

Fig. 26 is the external quantum efficiency diagram of the battery device of the seventh trans-type double-layer electron transport layer planar battery structure;

Fig. 27 is the steady-state current output diagram of the battery device with the planar battery structure of the trans-type double-layer electron transport layer in Example 7;

Fig. 28 is a long-term stability test chart of the battery device with the planar battery structure of the trans-type double-layer electron transport layer in the seventh embodiment under air atmosphere.

detailed description

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

_The present invention provides a surface _- modified CeO2 nanometer material, the surface of CeO2 nanometer particles is wrapped or adsorbed with bipolar organic molecules, so that the _CeO2 nanometer material can be uniformly dispersed in polar solvents and nonpolar solvents at the same time .

In one embodiment of the present invention, the carbon chain length of the main chain of the bipolar organic molecule is not more than five carbon atoms. The bipolar organic molecule is acetylacetone. Acetylacetone can volatilize at low temperature, even if it is not wrapped _on the surface of CeO2 nanoparticles, it can also volatilize without affecting product performance. Preferably, the particle size of the CeO ₂ nanoparticles is 1 nm˜100 nm. _CeO2 nanoparticles with different crystal structures are applicable. Further, the molar ratio of the acetylacetone to the CeO ₂ nanoparticles is less than 10000:1. With the prolongation of the surface modification reaction time, more acetylacetone was adsorbed on the surface of CeO ₂ nanoparticles, and the dispersion of the modified product was better, but the corresponding electrical conductivity would be slightly reduced.

Figure 1 is a field emission transmission electron microscope image of unmodified CeO2 nanoparticles; Figure ₂ (a), Figure ₂ (b) is a high-resolution transmission electron microscope image and selected area of unmodified CeO2 nanoparticles Diffraction pattern; Fig. 3 is the XRD diffraction pattern of unmodified _{CeO2nanoparticles} , as can be seen from the above three figures, _{CeO2Nanoparticle} particle size range is 8nm～14nm (its particle size is constant before and after modification), modified The monodisperse CeO ₂ nanoparticle crystal form self-assembled arrangement used for sex, the main exposed crystal plane spacing is 0.262 nanometers, which belongs to the (200) crystal plane, and the crystal surface activity energy is higher than other crystal planes, which is beneficial to the particle surface modification. , CeO ₂ nanoparticles belong to the cubic crystal system, and the positions of the five characteristic peaks are 28.549°, 33.077°, 47.483°, 56.342° and 69.416°, respectively corresponding to (111), (200), (220), (311) and (400) and other five crystal planes.

Fig. ₄ is CeO in the embodiment of the present invention Modification schematic diagram of nanoparticle, as can be seen from the figure, see the clean organic molecule that the surface wrapping of CeO nanoparticle is desorbed by longer carbon chain length oleic _acid organic molecule and obtains Nanoparticles, followed by surface modification treatment, acetylacetone organic molecules with shorter carbon chain lengths are adsorbed _on the surface of CeO2 nanoparticles to obtain modified _CeO2 nanoparticles. Fig. 5 is in the embodiment of the present invention in the surface modification process CeO ₂ The infrared spectrum comparison diagram of the nanoparticle of different stages, can know the surface adsorption state of the CeO ₂ nanoparticle of different stages in the surface modification process in the surface modification process from the figure, original CeO ₂ Nanoparticles can clearly see the characteristic peak of oleic acid. With the desorption reaction of alkaline solvent, it can be seen that the characteristic peak of oleic acid is weakened at light wavenumber 2925 and light wavenumber 2855, but at light wavenumber 1737 The characteristic peaks of acetylacetone have completely disappeared. At this time, the nanoparticles are cerium oxide nanoparticles without oleic acid coating. After the surface modification treatment of acetylacetone, the characteristic peaks of acetylacetone can be seen in the range of light wavenumber 3000-2500 The shift of peak shape and peak position may be due to the combination of _two isomers of acetylacetone with CeO2 nanoparticles.

The present invention also provides a nano-ink, which includes a solvent, and also includes the above-mentioned surface-modified CeO ₂ nano-material, and the surface-modified CeO ₂ nano-material is uniformly dispersed in the solvent. In the nano-ink, the mass concentration of the surface-modified CeO2 nano _- material can be 0-3 g/ml.

The present invention also provides an electron transport layer for batteries, which is prepared by using the above-mentioned nano-ink, and its roughness is less than 1 nm. Common methods of nano-ink film formation such as spin coating, drop coating, doctor blade coating and extrusion coating can be used to obtain an electron transport layer with a single layer thickness of 1 nanometer to 1000 nanometers. Polar and non-polar solutions can be used alternately to prepare multilayer electron transport layers.

The present invention also provides perovskite solar cells with three structures, wherein the perovskite solar cells with three structures are: (1) a formal planar perovskite solar cell, which includes a conductive substrate, an electron transport layer, a perovskite solar cell Ore absorbing layer, hole transport layer and metal electrode, the conductive substrate, electron transport layer, perovskite light absorbing layer, and hole transport layer are stacked sequentially, the metal electrode is electrically connected to the hole transport layer, the The electron transport layer is the electron transport layer as defined above, and its thickness is less than 100 nm to ensure the light transmittance of the electron transport layer. (2) trans-type single-layer electron transport layer planar perovskite solar cell, which includes a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, an electron transport layer and a metal electrode, the conductive substrate, the hole transport layer, The perovskite light-absorbing layer and the electron transport layer are stacked sequentially, the metal electrode is electrically connected to the electron transport layer, and the electron transport layer is the electron transport layer as defined above. (3) Trans-type double-layer electron transport layer planar perovskite solar cell, which includes a conductive substrate, a hole transport layer, a perovskite light-absorbing layer, a first electron transport layer, a second electron transport layer and a metal electrode, the A conductive substrate, a hole transport layer, a perovskite light-absorbing layer, a first electron transport layer, and a second electron transport layer are sequentially stacked, the metal electrode is electrically connected to the second electron transport layer, and the second electron transport layer For the electron transport layer as defined above, the electrical conductivity of the first electron transport layer is not less than the electrical conductivity of the second electron transport layer.

In order to further illustrate the modified CeO ₂ nanoparticles and products thereof of the present invention, the following will be further elaborated in conjunction with specific examples.

Embodiment 1, comprises the steps:

(1) Weigh 2 grams of cerium nitrate hexahydrate, add to a 500-ml beaker and stir, and add tert-butylamine dropwise under the condition of an ice-water bath until the pH is 8;

(2) Take 150 milliliters of the solution described in step (1) and add it to a 500 milliliter reaction kettle, add an equal volume of toluene and add 2 milliliters of oleic acid, and leave it to stand without stirring;

(3) Move the reaction kettle filled with about 60% of the step (2) into an oven with a constant temperature of 180 degrees Celsius, react for 24 hours and cool to room temperature, take it out, take the upper layer of brown clear liquid to obtain the toluene of cerium oxide wrapped in oleic acid solution;

(4) Take 30 milliliters of the toluene solution of cerium oxide coated with oleic acid described in step (3) and mix it with 30 mL of dehydrated ethanol, stir and ultrasonically make it fully separated, and centrifuge at a speed of 8000 r/min to obtain dark brown oil Acid-coated cerium oxide nanoparticles;

(5) repeat step (4) three times to remove excessive oleic acid in the solution, obtain the cerium oxide nanoparticles of brown oleic acid coating;

(6) Get 2 grams of the cerium oxide particles wrapped by oleic acid in step (5) and redisperse them in 20 ml of toluene solvent, and ultrasonically disperse them fully to obtain a toluene solution of cerium oxide wrapped by oleic acid;

(7) Get a 40% aqueous solution of 20 milliliters of tetrabutylammonium hydroxide, and add dropwise in the toluene solution of the cerium oxide wrapped with oleic acid described in step (6). Oscillation, ultrasonic to fully respond;

(8) Add absolute ethanol to the solution described in step (7), and transfer all the reacted solution to a 100 ml centrifuge tube. At a speed of 6000r/min, three layers of products separated from each other were obtained, the supernatant was poured off, and milky yellow precipitate was obtained. Repeat the above steps to wash three times with absolute ethanol to ensure that no impurity products remain. Obtain dispersed pure cerium oxide nanoparticles;

(9) Weigh 2 grams of dispersed pure cerium oxide nanoparticles described in step (8), add 20 milliliters of acetylacetone, oscillate and ultrasonically disperse until there are no obvious particles;

(10) After repeatedly stirring the solution described in step (9), and ultrasonicating for 48 hours, the acetylacetone solution of cerium oxide was obtained by filtering through a filter membrane with an aperture of 220 nanometers;

(11) The filtered solution in step (10) is added into a rotary evaporator to remove excess acetylacetone. The water temperature of the rotary evaporator is controlled at 40-100 degrees Celsius, and the air pressure is 0-80 mPa to obtain a dark red slurry. In this embodiment, the molar ratio of acetylacetone to CeO ₂ nanoparticles is less than 10000:1. The mass of acetylacetone adsorbed _on CeO2 nanoparticles has an upper limit value, and its adsorption amount will not further increase with the improvement of reaction conditions.

According to the above method, CeO ₂ nanoparticles with an original particle size of 1 nm to 100 nm can be successfully modified, and the particle size of the modified CeO ₂ nanoparticles remains unchanged.

Embodiment 2, comprises the steps:

(1) Steps for configuring the modified cerium oxide solution: disperse the cerium oxide slurry described in step (11) of Example 1 in an ethanol solvent to obtain a modified cerium oxide solution.

(2) Cleaning steps: select indium-doped tin oxide (ITO) glass with a square resistance of 5-25 ohms and a transmittance of 70%-90% as the substrate, and then clean it with detergent, distilled water, ethanol and acetone in sequence , treated with oxygen plasma beam for 10 minutes after nitrogen drying;

(3) Preparation of the modified cerium oxide film: get 70 microliters of the solution described in step (1) and spin-coat it on the surface of the indium-doped tin oxide (ITO) described in step (2), at a speed of 5000 revolutions per minute After the solution was spin-coated at a high speed for 30 seconds, it was placed on a hot stage at 80 degrees Celsius and heated for 10 minutes to obtain a modified cerium oxide film.

Fig. 6 is the optical photo comparison diagram of the CeO nanoparticle dispersion state in the solvent at different stages in the surface modification process of Example ₂ , as can be seen from the figure, clean cerium oxide is more difficult to disperse in the solvent, and surface modification must be carried out to improve The dispersibility of the material, the surface-modified CeO2 nanomaterials can be well dispersed in _two solvents with different polarities, and a clear and transparent solution with slightly different colors can be obtained;

Fig. 7 is the front scanning electron microscope figure of the film prepared by the CeO2 nanoparticle after the surface modification of embodiment _two , as can be seen from the figure, by the modified CeO2 _The film prepared by the nanoparticle is continuous, flat, without pinholes, and the surface The modified CeO2 nanoparticles improved the mechanical properties of the film prepared by the surface _- modified CeO2 nanoparticles due to the improved dispersibility in the solvent _;

Fig. ₈ is the atomic force microscope figure of the thin film prepared by the CeO2 nanoparticle after the surface modification of embodiment _two , as can be seen from the figure, the CeO2 nanoparticle prepared film after the surface modification is very smooth, and the local roughness is only 0.26 nanometers , can reduce the influence of interfacial layer fluctuations on the efficiency of planar structure perovskite solar cells. In practical engineering, multiple electron transport layers _were prepared using the modified CeO2 nanoparticles of the present invention, and their roughnesses were 0.14 nm, 0.29 nm, 0.56 nm, and 0.79 nm, all less than 1 nm.

Fig. ₉ is the transmittance spectrogram of the thin film prepared by the CeO2 nanoparticle after the surface modification of embodiment _two , as can be seen from the figure, the light transmittance of the thin film prepared by the CeO2 nanoparticle after the surface modification is high, satisfying as calcium Requirements for the window layer of titanium oxide solar cells;

Fig. ₁₀ is the fluorescence spectrogram of the CeO2 nanoparticle preparation film after embodiment _two surface modification, as can be seen from the figure, the CeO2 nanoparticle preparation film after the surface modification has obvious fluorescent effect in the ultraviolet region, can be used for The destructive ultraviolet light of perovskite is converted into visible light that can be absorbed by perovskite, which can improve the external quantum efficiency of perovskite solar cells while protecting the perovskite light-absorbing layer.

Fig. 11 is the ultraviolet photoelectron spectrum (UPS, Ultroviolet Photoelectron Spectrometer) figure of the CeO2 nanoparticle preparation film after embodiment _two surface modification, as can be seen from the figure, the modified CeO2 nanoparticle is a natural n _- type semiconductor material , the work function value of CeO ₂ nanoparticles after surface modification is -4.12 electron volts (eV), that is, the position of Fermi level is -4.12 electron volts from the vacuum level, and the maximum value of CeO ₂ nanoparticles after surface modification The valence band position is 3.44 electron volts (eV), that is, the position of the valence band top (VB) from the Fermi level is 3.44 electron volts, and the valence band position of cerium oxide can be calculated to be -7.56 electron volts (eV);

Fig. 12 is the CeO after the surface modification of embodiment _two Nanoparticles prepare the band gap (Bandgap) figure of thin film, as can be seen from the figure, the CeO after the surface modification The band _gap of the nanoparticles is 3.5 electron volts (eV) , that is, the distance between the conduction band position of cerium oxide and the valence band position is 3.5 electron volts, and the conduction band position of cerium oxide can be calculated to be -4.06 electron volts (eV);

Fig. 13 is the X-ray photoelectron spectrum (XPS, X _- ray Photoelectron Spectrometer) figure of the film prepared by the CeO2 nanoparticle after the surface modification of embodiment _two , as can be seen from the figure, the CeO2 film prepared by the nanoparticle after the surface modification The binding energy position of the Ce element is between 880eV and 920eV, and the binding energy position of the O element is between 530eV and 540eV;

Fig. 14 is the high-resolution X-ray photoelectron spectrum of the cerium element of the thin film prepared by CeO2 nanoparticle after the surface modification of embodiment _two , as can be seen from the figure, the cerium element of 3d _5/2 orbit is composed of trivalent cerium and tetravalent cerium Two valence states, among which trivalent cerium can split into two orbitals u'(v') and u ₀ (v ₀ ), and tetravalent cerium can split into u"'(v"'), u"(v") and u(v) three orbitals, after integrating the curves, it can be obtained that the atomic ratios of trivalent cerium and tetravalent cerium are 60.28 at.% and 39.72 at.% respectively;

Fig. 15 is the high-resolution X-ray photoelectron spectrogram of the oxygen element of the thin film prepared by the CeO2 nanoparticle after the surface modification of embodiment _two , as can be seen from the figure, the oxygen element of 1s track has three characteristic peaks, wherein, and trivalent state The combination of cerium with tetravalent state and the binding energy of carbon-oxygen bond on the particle surface are at 536.85, 534.55 and 532.05 electron volts respectively, which further illustrates the surface state of the particle. There are acetylacetone with shorter carbon chain length molecular adsorption.

Embodiment 3, comprises the steps:

(1) Cleaning steps: select indium-doped tin oxide (ITO) glass with a square resistance of 5-25 ohms and a transmittance of 70%-90% as the substrate, and then clean it with detergent, distilled water, ethanol and acetone in sequence , treated with oxygen plasma beam for 10 minutes after nitrogen drying;

(2) Preparation of the electron transport layer solution: take the cerium oxide slurry described in step (11) of Example 1, disperse it in a chlorobenzene solvent at a mass concentration of 5 mg per milliliter, stir at room temperature until completely dispersed, and obtain the cerium oxide slurry Chlorobenzene solution of cerium.

(3) Preparation of the electron transport layer: get the solution described in step (2) and spin-coat it on the ITO substrate described in step (1), after spinning the solution for 30 seconds at a speed of 5000 rpm, place it at 80 degrees Celsius heated on a hot stage for 10 minutes to obtain a dense cerium oxide electron transport layer about 20 nm thick.

(4) Preparation steps of the perovskite solution: PbI ₂ and MAI are mixed to form a mixture, wherein PbI ₂ accounts for 70% by molar ratio, and is dissolved in a mixed solvent of DMF and DMSO, wherein DMF accounts for 80% by volume. Stir at room temperature until all dissolve to obtain MAPbI ₃ perovskite solution;

(5) Preparation of the perovskite layer: Spin-coat the prepared perovskite solution on the cerium oxide electron transport layer, spin-coat the solution at a speed of 6000 rpm for 30 seconds, and place it on a hot stage at 100 degrees Celsius for heating After 10 minutes, the solvent evaporates to form a perovskite light-absorbing layer about 350 nanometers thick;

(6) Preparation steps of the hole transport layer solution: take 80 mg of Spiro-OMeTAD powder, add 30 microliters of tributyl phosphate (TBP), 35 microliters of lithium bis(trifluoromethylsulfonyl)imide (LiTFSI) The acetonitrile solution and 1 ml of chlorobenzene were shaken to dissolve completely, and oxidized in dry air for 12 hours to obtain the chlorobenzene solution of Spiro-OMeTAD.

(7) Preparation of the hole transport layer: the configured Spiro-OMeTAD solution was spin-coated on the perovskite light-absorbing layer to form a hole transport layer with a thickness of about 100 nanometers.

(8) The preparation step of the metal counter electrode: using vacuum evaporation coating equipment, a gold electrode with a thickness of 100 nm is evaporated on the hole transport layer to obtain a solid-state formal planar perovskite solar cell.

Fig. 16 is a battery device structure diagram of the formal planar perovskite solar cell of the third embodiment, and Fig. 17 is a photovoltaic curve of the formal planar perovskite solar cell device of the third embodiment under a standard sunlight intensity, as can be seen from the above two figures, Films prepared from surface _- modified CeO2 nanoparticles are used as window layers in formal planar perovskite solar cells. Thanks to their high transmittance, the prepared formal planar solar cells have a high short-circuit current.

Embodiment 4, comprises the steps:

(1) Cleaning steps: select fluorine-doped tin oxide (FTO) glass with a square resistance of 5-25 ohms and a transmittance of 70%-90% as the substrate, and then clean it with detergent, distilled water, ethanol and acetone in sequence , treated with oxygen plasma beam for 10 minutes after nitrogen drying;

(2) Preparation steps of the hole transport layer solution: at room temperature, weigh a certain amount of nickel acetylacetonate, lithium acetate and magnesium acetate, mix according to the stoichiometric ratio Ni:Li:Mg=80:5:15, dissolve in In the acetonitrile solution, a precursor solution with a nickel molar concentration of 0.02 moles per liter was obtained.

(3) Preparation of the hole transport layer: Place the conductive glass treated in step (1) upwards on a heating platform at 600 degrees Celsius, and use oxygen to pressurize and atomize the precursor solution described in step (2). 50 ml of precursor solution is sprayed onto a high-temperature conductive surface, and a dense and continuous nickel-magnesium-lithium-oxygen (NiMgLiO) dense layer is rapidly deposited, with a film thickness of about 20 nanometers. Continue annealing at this temperature for 60 minutes after spraying;

(4) The preparation step of perovskite layer solution: same as embodiment 2 step (4);

(5) Preparation of the perovskite layer: Spin-coat the configured perovskite solution on the nickel-magnesium-oxylithium electron transport layer, spin-coat the solution at a speed of 6000 rpm for 30 seconds, and place it on a hot stage at 100 degrees Celsius Heating on top for 10 minutes, the solvent evaporates to form a perovskite light-absorbing layer about 350 nanometers thick;

(6) Preparation steps of the electron transport layer solution: dilute the solution described in step (6) in Example 1 with a toluene solvent at a mass concentration of 5 mg per milliliter to obtain a toluene solution in which oleic acid wraps cerium oxide;

(7) Preparation of the electron transport layer: get the solution described in step (6) and spin-coat it on the perovskite layer described in step (5), after spinning the solution for 30 seconds at a speed of 5000 revolutions per minute, place it at 80 Heated on a hot stage at 100°C for 10 minutes to obtain a cerium oxide electron transport layer wrapped with oleic acid with a thickness of about 50 nanometers.

(8) Preparation steps of the metal counter electrode: use vacuum evaporation coating equipment to evaporate a layer of silver electrode with a thickness of 100nm on the hole transport layer to obtain a solid-state all-inorganic interfacial layer of trans planar perovskite solar energy Battery.

Fig. 18 is the battery device structure diagram of the battery device of the embodiment four trans-type single-layer electron-transporting layer planar battery structure, and Fig. 19 is the battery device of the embodiment four-trans-type single-layer electron-transporting layer planar battery structure under a standard sunlight intensity The photovoltaic curve below, as can be seen from the above two figures, the thin film prepared by oleic acid-wrapped cerium oxide is used as the electron transport layer in the trans-type single-layer electron transport layer planar cell, and the excessive molecular distance blocks the charge in the electron transport layer. Migration greatly reduces the photovoltaic performance of solar cells, resulting in a weird "S" type photovoltaic characteristic curve.

Embodiment 5, comprises the steps:

The first five steps, ie step (1) to step (5), are the same as in Example 4.

(6) Preparation steps of the electron transport layer solution: the same as in Example 2 step (2);

(7) Preparation of the electron transport layer: get the solution described in step (6) and spin-coat it on the perovskite layer described in step (5), after spinning the solution for 30 seconds at a speed of 5000 revolutions per minute, place it at 80 Heating on a hot stage at 100°C for 10 minutes to obtain a dense cerium oxide electron transport layer about 50 nm thick.

(8) Preparation steps of the metal counter electrode: use vacuum evaporation coating equipment to evaporate a layer of silver electrode with a thickness of 100nm on the hole transport layer to obtain a solid-state all-inorganic interfacial layer of trans planar perovskite solar energy Battery.

Fig. 20 is the battery device structural diagram of the battery device of the embodiment five trans-type single-layer electron-transporting layer planar battery structure, and Fig. 21 is the battery device of the embodiment five-trans-type single-layer electron-transporting layer planar battery structure under a standard sunlight intensity The photovoltaic curve below, as can be seen from the above two figures, the film prepared by the surface modified CeO ₂ nanoparticles is used as the electron transport layer in the trans-type single-layer electron transport layer planar cell, and the molecular distance in the electron transport layer is shortened, which is beneficial to The migration of charges in the electron transport layer improves the photovoltaic performance of solar cells.

Embodiment 6, comprises the steps:

The first five steps, ie step (1) to step (5), are the same as in Example 4.

(6) Preparation steps of the electron transport layer solution: at room temperature, weigh a certain amount of PCBM powder, dissolve it in the chlorobenzene solution according to the mass concentration of 20 mg per milliliter, and stir until completely dissolved at 40 degrees Celsius to obtain the chlorobenzene of PCBM solution;

(7) Get the solution described in step (6) and spin-coat it on the perovskite layer described in step (5), after spinning the solution for 30 seconds at a speed of 5000 rpm, place it on a hot stage at 80 degrees Celsius for heating After 10 minutes, a PCBM lower electron transport layer about 50 nm thick was obtained.

(8) Preparation steps of the metal counter electrode: use vacuum evaporation coating equipment to vapor-deposit a layer of silver electrode with a thickness of 100 nm on the hole transport layer to obtain a solid trans-planar perovskite solar energy with a double electron transport layer. Battery.

Fig. 22 is the battery device structure diagram of the battery device of the embodiment six trans-type single-layer electron-transporting layer planar battery structure, and Fig. 23 is the battery device of the embodiment six-trans-type single-layer electron-transporting layer planar battery structure under a standard sunlight intensity The photovoltaic curve below shows that the film prepared by PCBM is used as an electron transport layer in the trans-type single-layer electron transport layer planar cell. The conductivity of PCBM is better than that of CeO ₂ nanoparticles after surface modification, but due to The conduction band position of PCBM is too high, and the contact with the silver electrode is a Schottky contact. There is a strong non-radiative recombination on the interface between the two, which reduces the photovoltaic performance of the solar cell and obtains a similar "S" type photovoltaic characteristic curve.

Embodiment 7, comprises the steps:

The first seven steps, ie step (1) to step (7), are the same as in Example 6.

(8) Preparation steps of the upper electron transport layer solution: take the cerium oxide slurry described in step (11) of Example 1, disperse it in a methanol solvent at a mass concentration of 5 mg per milliliter, stir at normal temperature until completely dispersed, and obtain Methanol solution of cerium oxide.

(9) At a speed of 6000 rpm, apply 150 microliters of the solution described in step (7) dropwise on the PCBM electron transport layer described in step (7), and place it on a hot stage at 80 degrees Celsius After heating for 10 minutes, a cerium oxide upper electron transport layer with a thickness of about 50 nanometers was obtained.

(10) Preparation steps of the metal counter electrode: use vacuum evaporation coating equipment to vapor-deposit a layer of silver electrode with a thickness of 100 nm on the hole transport layer to obtain a solid-state double electron transport layer trans planar perovskite solar energy Battery.

Fig. 24 is a structural diagram of the battery device of the seventh embodiment of the trans-type double-layer electron-transporting layer planar battery structure, and Fig. 25 is the battery device of the embodiment 7 trans-type double-layer electron-transporting layer planar battery structure under a standard sunlight intensity Photovoltaic curve, Fig. 26 is the external quantum efficiency figure of the battery device of embodiment seven trans-type double-layer electron transport layer planar battery structures, as can be seen from the above three figures, the CeO after surface modification _The film prepared by nanoparticles is used as the upper layer electron transport Layer (that is, the second electron transport layer) is used in the trans-double-layer electron transport layer planar battery. The double-layer electron transport layer not only improves the charge transmission speed in the electron transport layer, but also eliminates the Schottky on the interface. The external quantum effect of the battery device is greatly improved, and the photovoltaic performance of the solar cell is improved;

Fig. 27 is the steady-state current output diagram of the battery device of the seventh trans-type double-layer electron-transporting layer planar battery structure, and Fig. 28 is the output of the battery device of the seventh trans-type double-layer electron-transporting layer planar battery structure under air atmosphere Long-term stability test chart. From the above two figures, it can be seen that the film prepared by surface-modified CeO ₂ nanoparticles, because the surface acetylacetone organic molecules strengthen the intermolecular force, the compactness of the film is improved, which not only blocks the calcium inside the battery device The dissipation of organic molecules of titanium ore also prevents the erosion of external water and oxygen on battery devices, the maximum power point current output is more stable, and the long-term stability in air atmosphere is also improved.

Due to similar properties, the perovskite materials described in the present invention include ABX ₃ , where A=methylamine ion (MA, CH ₃ NH ₃ ⁺ ), cesium ion (Cs ⁺ ), etc. or both Or mixture, B = lead ion (Pb ²⁺ ), stannous ion (Sn ²⁺ ), etc. or a mixture of both, X = chloride ion (Cl ^- ), bromide ion (Br ^- ), iodide ion (I ^- ), etc. or a mixture of both.

Those skilled in the art can easily understand that the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention, All should be included within the protection scope of the present invention.

Claims (10)

1. the CeO that a kind of surface is modified₂Nano material, it is characterised in that CeO₂Nano grain surface is enclosed with organic point of bipolarity Son, so that the CeO₂Nano material can be simultaneously dispersed in polar solvent and non-polar solven.

2. the CeO that a kind of surface as claimed in claim 1 is modified₂Nano material, it is characterised in that organic point of the bipolarity The carbon chain lengths of sub- main chain are not more than five carbon atoms.

3. the CeO that a kind of surface as claimed in claim 1 or 2 is modified₂Nano material, it is characterised in that the bipolarity is organic Molecule is acetylacetone,2,4-pentanedione.

4. a kind of modified CeO in surface as described in one of claim 1-3₂Nano material, it is characterised in that CeO₂Nanometer The particle diameter of grain is 1nm~100nm.

5. the CeO that a kind of surface as claimed in claim 3 is modified₂Nano material, it is characterised in that the acetylacetone,2,4-pentanedione and institute State CeO₂The mol ratio of nano particle is less than 10000:1.

6. a kind of nanometer ink, it includes solvent, it is characterised in that also change including the surface as described in one of claim 1-5 The CeO of property₂Nano material, the modified CeO in the surface₂Nano material is dispersed in a solvent.

7. a kind of electron transfer layer for battery, it is characterised in that it uses nanometer ink system as claimed in claim 6 Standby, its roughness is less than 1nm.

8. a kind of formal plane perovskite solar cell, it includes conductive substrates, electron transfer layer, perovskite light-absorption layer, sky Cave transport layer and metal electrode, the conductive substrates, electron transfer layer, perovskite light-absorption layer, hole transmission layer are stacked gradually, The metal electrode is electrically connected with the hole transmission layer, it is characterised in that

The electron transfer layer is the electron transfer layer defined in claim 7, and its thickness is less than 100nm to ensure State the light transmission rate of electron transfer layer.

9. a kind of trans single layer electronic transmits layer plane perovskite solar cell, it is characterised in that

It includes conductive substrates, hole transmission layer, perovskite light-absorption layer, electron transfer layer and metal electrode,

The conductive substrates, hole transmission layer, perovskite light-absorption layer, electron transfer layer are stacked gradually, the metal electrode and institute Electron transfer layer electrical connection is stated,

The electron transfer layer is the electron transfer layer defined in claim 7.

10. a kind of trans two-layer electronic transmission layer plane perovskite solar cell, it is characterised in that it include conductive substrates, Hole transmission layer, perovskite light-absorption layer, the first electron transfer layer, the second electron transfer layer and metal electrode,

The conductive substrates, hole transmission layer, perovskite light-absorption layer, the first electron transfer layer, the second electron transfer layer layer successively Folded, the metal electrode is electrically connected with second electron transfer layer,

Second electron transfer layer is the electron transfer layer defined in claim 7,

Electrical conductivity of the electrical conductivity of first electron transfer layer not less than the second electron transfer layer.